What must be proven in a (California) product liability case?

In California, we use typically the “consumer expectation test” to determine whether or not a product is defective. So in some cases, all that’s required is the plaintiff to tell the facts of the story, and what happened with the product. And the jury, from using their own commonsense and judgement, can decide that that product did not behave or function like a reasonable consumer would have expected it to. And that’s all it’s required. In other (California product liability) cases, expert testimony might be required to help a juror determine whether or not that product functioned or behaved like a reasonable consumer would have expected it to have behaved.

For example, in a case involving a durable waterproofing spray which comes in a can. That product is a very simple product, and when one sprays it, inhales the contents of the gas mist accidentally, or by mistake, then that product didn’t behave like a reasonable… I’m sorry… And that product causes a lung injury. A reasonable consumer would not expect that using that spray and inhaling it accidentally would cause a lung injury. So in a case like that, the plaintiff might just hope that a jury would see that a reasonable consumer wouldn’t expect to be injured by spraying this durable waterproofing product. However, a good plaintiff’s attorney would probably hire a pulmonologist or some other medical doctor to help show that the contents within the spray get into the lungs and cause scarring of the lungs. So those are some of the things that we use in California, typically expert witness testimony, to help prove that the product is defective.